Photon Imager is a modular system for the non-invasive detection, localization and quantification of dynamic optical signal - bioluminescence or fluorescence – from live animals. A unique photon counting technology makes it extremely ensitive from the very start of image acquisition and enables the unparalleled kinetic recording of dynamic processes without the need for setting acquisition time, or pixel binning prior to imaging. Photon Imager continuously displays the light distribution during an experiment and image acquisition can be stopped at any time. This is a key advantage for bioluminescence imaging and can open new horizons for fluorescence imaging. Unlike other Pre-Clinical Imaging systems, the real-time imaging capability of *the Photon Imager delivers impressive performance, whilst its modular design philosophy ensures that the systems capabilities can be extended, as further state-of-the-art imaging technologies become available.